To make sugar glass: mix all ingredients in large saucepan. Bring to boil. Use candy thermometer& boil until mixture reaches 300degrees. Stirring constantly. Pour into baking pan & allow to cool.
Make blood: mix cornstarch and syrup in large bowl. Slowly pour in water till reaches consistency of blood. Stir in food coloring. Stab broken glass into cupcakes. Sprinkle with blood.